Athenahealth IPO Soars 97%

Year's Best Debut
Adds Some Zest
To Slow September

Shares of medical-software company Athenahealth Inc. added some zing to an otherwise slow market for new stock issues, turning in the best first-day performance of any deal so far this year.

The initial public offering of the Watertown, Mass., company closed at $35.50 a share, up 97% from its IPO price of $18. Its debut gain topped that of virtualization-software company VMware Inc., which was up 76% on its first day of trading in...